Mouth stuffing gags are similar to mouth opening gags but they fill the mouth with the body of the gag, restricting tongue movement far more. This has the effect of making speech even more difficult.

Some of the styles include the ball gag, bit gag, butterfly gag, cleave gag, penis gag, rope gag and the stuff gag. The so-called ‘fornophilic gag’ sometimes comes under this description as a variation on the penis gag, allowing attachment of an object on the outside e.g. dildo or toiletbrush, to humiliate the wearer or allow them to use the attachment as their master instructs.